The invention is directed to a method of producing an electrical contact with low contact resistance on a semiconductor body, which method is, in particular, suitable for luminescence diodes consisting of semiconductor material and which also is suitable to secure the semiconductor body on an electrically conductive body acting as heat sink.
In the past, low resistance contacts applied to luminescence diodes composed of semiconductor material, in particular gallium phosphide, were produced by alloying such contacts at temperatures of approximately 500.degree.C. In this case a cleavage surface of the crystal was alloyed, as a whole, onto the heat sink. In such alloying process the reflective power for the luminescent radiation produced within the semiconductor material was considerably reduced at the boundary surface gallium phosphide-metal contact, so that the light entering the alloy layer was practically completely absorbed therein.
In order to increase the efficiency of luminescence diodes, it would therefore be advantageous to employ metal contacts which are alloyed on small areas and which possess a reflection coefficient as high as possible for the luminescent radiation falling upon such boundary surface. In the production of such contacts, initially a SiO.sub.2 layer of approximately 5000 AE was applied to the surface to be alloyed and into such SiO.sub.2 layer were etched holes whose total areas formed approximately 10% of the surface to be alloyed-on. Subsequently, metallic contact material was vapour-deposited upon such SiO.sub.2 layer and the vaporized semiconductor body was then alloyed, at high temperatures, into the heat sink. The metal contact produced in accordance with this improved method possessed reduced absorption losses, but as a result of the relatively thick SiO.sub.2 layer, the heat resistance between the semiconductor body and the heat sink was considerably increased.
The present invention therefore has as its objective the provision of an ohmic contact for luminescence diodes which are to be adhered to a heat sink, in which the contact exhibits low absorption losses and in addition thereto a low heat resistance.